Projection lamp having resilient support means for dichroic reflector



uFully 18, 1967 J. F. MICHAEL 3,331,980 PROJECTION LAMP HAVING RESILIENT SUPPORT MEANS FOR DICHROIC REFLECTOR Filed Nov. 21, 1963 INVENTOR Jacob F. Michael ATTORNEY United States Patent 3,331,980 PRQJECTION LAMP HAVING RESILIENT SUPPORT MEANS FOR DICHROIC RE- FLECTOR Jacob F. Michael, Paramus, N.J., assignor to Westing- Filed Nov. 21, 1963, Ser. No. 325,370 2 Claims. (Cl. 313-113) The present invention relates to projection lamps for projecting a beam of light, such as are commonly utilized in connection with motion picture and film-slide showing, and pertains more especially to such a lamp with a dichroic reflector.

Projection lamps utilizing dichroic reflectors which are Wave-length selective so as to reflect visible radiations while transmitting infra-red radiations therethrough are known to the art. Such reflectors must necessarily be formed of a base material that is transparent to the infrared radiations while at the same time the dichroic coating applied thereto reflects only the visible radiations as a beam in a desired direction. Heretofore one of the major difiiculties with a dichroic reflector projection lamp has been that of retaining the reflector accurately positioned within the lamp throughout the useful life thereof which is an absolute necessity in order to produce and maintain the light beam in a definite direction.

It is accordingly the primary object of the present invention to provide a projection lamp having a dichroic reflector and wherein such reflector remains in proper focal position within the lamp throughout its entire useful life.

Another object of the present invention is the provision of a projection lamp having a dichroic reflector accurately positioned and retained therein without the necessity of sealing such dichroic reflector to any support wires.

A further object of the present invention is the provision of a projection lamp provided with a dichroic reflector therein which is resiliently supported so as to be retained in a definite focal position despite contraction and expansion of parts of such lamp during its useful life.

The foregoing objects of the present invention together with other objects which will become obvious to those skilled in the art from the following description are achieved by providing a projection lamp with a dichroic reflector which is locked in place by a metallic clip and hence retained in definite focal position within the lamp during its entire useful life. The leading-in and support wires pass through openings in the dichroic reflector and are resiliently connected thereto thus eliminating a difficult glass-to-metal seal while at the same time imparting dependable support to assist in maintaining the dichroic reflector in its proper position within the lamp.

The present invention can be readily understood by reference to the accompanying drawing wherein:

FIGURE 1 is a side elevational view partly in crosssection of a projection lamp provided with a dichroic reflector in accordance with the present invention;

FIG. 2 is a rear elevational view partly in cross-section and taken ninety degrees from that of FIG. 1;

FIG. 3 is a side elevational view similar to FIG. 1 but showing a slight modification which the present invention may take, and

FIG. 4 is a rear elevational view taken ninety degrees from that of FIG. 3.

Referring now more specifically to the drawing disclosing two modifications which the present invention may take, there is shown in FIG. 1 a projection lamp 5 comprising the usual electrically non-conducting vitreous envelope 6 with the customary base 7 aflixed thereto and having a keyed locating post 8. Such projection lamp 5 is provided with four contact pins 9-10 and 12-13 hermetically sealed to the envelope at 14 and passing outwardly of the base 7 from which they are appropriately insulated. Leading-in and supporting conductors 15 and 16 are welded to the contact pins 12 and 13 which thus form extensions thereof and at their upper extremity are provided with angularly extending ends 17 and 18 to which a vertically oriented incandescible filament 19 is accurately sesured so as to dispose it at a preselected position within the envelope 6.

For the purpose of focusing light from the filament 19 on the film aperture of a projection machine without the necessity of condensing lenses, the projection lamp 5 is provided with an ellipsoidal reflector 20, the substrate portion of which preferably is formed of vitreous material such as glass. The reflector 20 is so positioned and held With respect to the filament 19 within the envelope 6 that the reflected light beam emanating from the lamp 5 is of a fixed direction and dimension. This reflector 20 carries on its concave surface a conventional dichroic coating 21 which thus renders the reflector wave-length selective, resulting in light of visible wave-length being reflected and projected outwardly of the lamp 5 by the concave ellipsoidal surface in a predetermined directional area, while the infra-red wave-length radiations pass through the reflector and thus in a direction opposite to the optical system of the lamp and projector. Preferably the filament is positioned at or proximate that focus of the ellipsoidal reflector which is nearest to the reflector 20. The other reflector focus is located outside of the envelope 6.

To assist in maintaining the dichroic ellipsoidal reflector 20 in its definite predetermined position within the envelope 6 despite the relatively high temperature to which it is subjected, a metallic clip 22 is secured to the inner ends of the contact pins 910. This clip 22 may be formed of bent wire as shown in FIGS. 1 and 2 or constitute a metal stamping as seen in FIGS. 3 and 4. In either event such metallic clip 22 is provided with spaced projections which bear on the front and rear surfaces of the reflector 20 adjacent its peripheral edge, to thus form a slightly resilient support to compensate for contraction and expansion due to temperature changes and thus eliminate undue strain on the vitreous dichroic reflector 20.

It will be noted from the several figures that the angularly extending ends 17 and 18 of the leading-in and supporting conductors 15 and 16 pass through vertically spaced openings provided for the purpose in the reflector 20. Also to form a further upright slightly resilient support for this reflector 20 each of these conductor ends 17 and 18 are provided with a flanged eyelet 23 welded or staked thereto which bears against the dichroic reflecting surface since the flange portion is of greater diameter than the openings in the reflector. In the modification shown in FIGS. 1 and 2 a similar flanged eyelet 24 is welded or staked to these same conductor ends 17 and 18 but with the flanged portion thereof spaced a short distance from the rear surface of the reflector 20. The slightly resilient connection between the conductor ends 17 and 18 and the reflector 20 is then formed by a metallic coil spring 25, preferably molybdenum, disposed between the rear surface of the reflector and the flange portion of the rear eyelet 24, as shown in FIGS. 1 and 2. If desired the rear flanged eyelet 24 and coil spring 25 may be dispensed with and the slightly resilient connection made by a well known friction-type locknut 26 carried by the conductor ends 17 and 18 and bearing against the rear surface of the reflector 20, as shown in the modification of FIGS. 3 and 4.

It should thus be obvious to those skilled in the art that a projection type incandescent lamp is herein provided wherein a vitreous dichroic reflector forms an integral part of the interior of such lamp and is held securely in a definite position therein without the necessity of a permanent glass-to-metal seal. On the contrary the support for the reflector, although sufliciently reliable in nection thereof to its support was employed.

Although two specific modifications of the present invention have been herein shown and described, it is to be understood that still further modifications thereof may be made without departing from the spirit and scope of the appended claims.

I claim:

1. A projection lamp comprising:

(a) an envelope, e

(b) a metallic clip rigidly supported within said envelope,

(c) an electrically non-conducting ellipsoidal dichroic reflector, having predetermined focal points, secured to said metallic clip to retain said reflector in a predetermined position in the envelope throughout the useful life of said lamp,

(d) an incandescible filament positioned within said envelope and proximate that focus of said reflector which is nearer said reflector,

(e) a pair of leading-in and supporting conductors supported within said envelope and passing through openings in said reflector and connected to the respective ends of said filament,

(f) stop means secured to said leading-in and supporting conductors adjacent one side of said reflector,

(g) and resilient metallic means secured to said leading-in and supporting conductors adjacent the other side ofsaid dichroic reflector resiliently forcing said reflector against said stop means to maintain said filament and reflector in proper focal position relative to each other throughout the life of said lamp.

2. A projection lamp comprising:

(a) an envelope,

(b) a slightly resilient metallic retaining means rigidly supported within said envelope,

(0) an electrically non-conducting ellipsoidal dichroic reflector, having predetermined focal points, secured to said retaining means to retain said reflector in a predetermined position in the envelope throughout the useful life of said lamp,

(d) an incandescible filament positioned within said envelope and proximate that focus of said reflector which is nearer said reflector,

(e) a pair of leading-in and supporting conductors supported Within said envelope and passing through openings in said reflector and connected to the respective ends of said filament,

(f) flanged eyelet means secured to said leading-in and supporting conductors adjacent the side of said reflector facing said filament, and metallic coil spring means secured to said leading-in and supporting conductors adjacent the other side of said dichroic reflector and resiliently forcing said reflector against said flanged eyelet means to maintain said filament and reflector in proper focal position relative to each other throughout the life of said lamp.

References Cited UNITED STATES PATENTS JAMES W. LAWRENCE, Primary Examiner.

P. C. DEMEO, Assistant Examiner. 

1. A PORJECTION LAMP COMPRISING: (A) AN ENVELOPE, (B) A METALLIC CLIP RIGIDLY SUPPORTED WITHIN SAID ENVELOPE, (C) AN ELECTRICALLY NON-CONDUCTING ELLIPSOIDAL DICHROIC REFLECTOR, HAVING PREDETERMINED FOCAL POINTS, SECURED TO SAID METALLIC CLIP TO RETAIN SAIS REFLECTOR IN A PREDETERMINED POSITION IN THE ENVELOPE THROUGHOUT THE USEFUL LIFE OF SAID LAMP, (D) AN INCANDESCIBLE FILAMENT POSITIONED WITHIN SAID ENVELOPE AND PROXIMATE THAT FOCUS OF SAID REFLECTOR WHICH IS NEARER SAID REFLECTOR, 